Method and device for estimating motion parameters of crescent dune based on remote sensing image and medium

Abstract

The invention discloses a method and a device for estimating motion parameters of a crescent dune based on remote sensing images and a medium. The method comprises the following steps: acquiring optical remote sensing images covering a single crescent dune to be researched in any two periods; extracting a windward slope toe line, a leeward slope toe line and a sand ridge line of the crescent dune, and connecting two wing angular points of the dune as auxiliary lines; for each feature line, selecting a pixel point farthest from the auxiliary line as a feature point of the feature line; calculating the moving distance of each characteristic line between the two periods, and integrating the moving distances of the three characteristic lines to obtain the moving distance and speed of the crescent dune; and determining the moving directions of the windward slope toe line, the leeward slope toe line and the crescent dune according to the interconnection lines of the feature points of the windward slope toe line, the leeward slope toe line and the sand ridge line in the early-stage optical remote sensing image and the positive and negative values of the moving distance of the crescent dune. The method can improve the accuracy of estimating the motion parameters of the crescent dune.

Description

Technical Field

[0001] The invention belongs to the technical field of geodesy, and in particular relates to a method, a device and a medium for estimating movement parameters of a crescent-shaped sand dune based on remote sensing images. Background Art

[0002] As one of the main forms of sandstorm damage, dune movement destroys and buries facilities, buildings, roads, and farms, causing farmland desertification and grassland vegetation degradation, posing a serious threat to regional ecological security, infrastructure construction, and people's lives and property. Under the action of wind, the sand source material on the windward slope of the crescent-shaped sand dune is eroded and then accumulated on the leeward slope, causing the movement of the sand dune and the change of its morphology during the movement process. Accurately estimating the movement parameters of the sand dune can more accurately obtain the movement of the sand dune and understand the movement law of the sand dune.

[0003] There are two main methods for the morphological measurement and movement of a single crescent dune. The first method is to extract typical feature points of dunes based on satellite images, and calculate the overall movement parameters of dunes by tracking the change or average change of feature points at different times. Typical feature points include the center point of the foot line of the windward slope of the dune, the center point of the foot line of the leeward slope, the highest point of the sand ridge line, and the corner points of the two wings of the dune. In reality, the morphology of a single dune is constantly changing during movement, and it is difficult to determine the corresponding feature point position in the next period. The second method uses multiple feature points extracted from the dune in a certain period to calculate the centroid coordinates to represent the center position of the dune, and characterizes the overall movement parameters of the dune by the change parameters of the centroid coordinates of the dune in different periods. However, the complex wind conditions in the desert area lead to the most significant changes on the two wings of the dune. The centroid coordinates of the dune are calculated to find that the centroid is offset to the two wings of the dune, resulting in the distance and direction of the dune movement not being consistent with the actual movement of the dune. Summary of the invention

[0004] The present invention provides a method, a device and a medium for estimating motion parameters of a crescent-shaped sand dune based on remote sensing images, so as to improve the accuracy of estimating the motion parameters of a crescent-shaped sand dune.

[0005] In order to achieve the above technical objectives, the present invention adopts the following technical solutions:

[0006] A method for estimating motion parameters of crescent dunes based on remote sensing images, comprising:

[0007] Step 1, obtain any two periods of optical remote sensing images covering a single crescent-shaped dune to be studied;

[0008] Step 2, extract the following characteristic lines of the crescent-shaped sand dune from each optical remote sensing image: the foot line of the windward slope, the foot line of the leeward slope, and the sand ridge line, connect the two wing corner points of the crescent-shaped sand dune and use the connection line as an auxiliary line;

[0009] Step 3: For each feature line, select the pixel point farthest from the auxiliary line as the feature point of the feature line;

[0010] Step 4, for each characteristic line extracted from the two periods, based on the distance from the characteristic point of the characteristic line in each period to the characteristic line in another period, calculate the moving distance of the characteristic line between the two periods; and combine the moving distances of the three characteristic lines to obtain the moving distance and moving speed of the crescent dune between the two periods;

[0011] Step 5, determine the movement direction of the windward slope footline, leeward slope footline and crescent sand dune between the two periods based on the interconnected lines of the characteristic points of the windward slope footline, leeward slope footline and sand ridge line in the previous optical remote sensing image, as well as the positive and negative values ​​of the movement distance of the crescent sand dune between the two periods.

[0012] Furthermore, the optical remote sensing image is an optical satellite image with a resolution exceeding 10 meters.

[0013] Furthermore, for each characteristic line extracted from the two periods, based on the distance from the characteristic point of the characteristic line in each period to the characteristic line in another period, calculating the moving distance of the characteristic line between the previous and next periods specifically includes:

[0014] Suppose the characteristic lines extracted in the previous and next two phases are L1 and L2, and the corresponding characteristic points are A1 and A2 respectively;

[0015] Place feature lines L1 and L2 in the same layer based on their physical coordinate positions; then in this layer: find a point B2 on feature line L2, and the line B2A1 connecting point B2 and feature point A1 is the perpendicular line of feature line L2 at point B2, then the distance between feature point A1 and point B2 is the distance d from feature point A1 to feature line L2 1 ; Use the same method to obtain the distance d from the feature point A2 to the feature line L1 2 ;

[0016] Take the distance d 1 With distance d 2 The average value of is taken as the amplitude of the moving distance of the current calculation characteristic line between the previous and next periods;

[0017] Determine whether the vector angle between the direction from feature point A1 to feature point A2 and the southeast direction is less than 90 degrees: if the vector angle is less than 90 degrees, the moving distance between the previous and next periods of the currently calculated feature line is taken as a positive value; if the vector angle is greater than 90 degrees, the moving distance between the previous and next periods of the currently calculated feature line is taken as a negative value.

[0018] Furthermore, the average of the moving distances of the three characteristic lines, namely the sand ridge line, the foot line of the leeward slope, and the foot line of the windward slope, between the two periods is taken as the moving distance of the crescent dune between the two periods; and the moving speed of the crescent dune between the two periods is calculated according to the time interval T between the two periods; it is expressed as:

[0019]

[0020] In the formula, d and v are the moving distance and moving speed of the crescent dune between the two phases, respectively. s ,d b ,d y They respectively represent the moving distances of the three characteristic lines, namely the sand ridge line, the leeward slope foot line and the windward slope foot line, between the two periods.

[0021] Furthermore, step 5 of determining the moving direction specifically includes:

[0022] Step 5.1, connecting the feature points of each feature line extracted from the previous optical remote sensing image in pairs;

[0023] Step 5.2, record the characteristic points of the windward slope foot line, leeward slope foot line and sand ridge line as Y1, B1, S1 respectively, and obtain the interconnecting lines Y1B1, B1S1, Y1S1, then:

[0024] Calculate the two angles α between the connecting line Y1S1 and the north-south direction 1 ,α 2 : If the distance of movement of the crescent dune between the two phases is positive, then the azimuth of the windward slope foot line moving between the two phases takes two included angles α 1 ,α 2 If the distance of movement of the barchan dune between the two phases is negative, the azimuth of the windward slope foot line moving between the two phases is the angle between the two included angles α 1 ,α 2 The larger value of ;

[0025] Calculate the two angles β between the connecting line B1S1 and the north-south direction 1 ,β 2 :If the distance of movement of the crescent dune between the two phases is positive, then the azimuth of the movement of the foot line of the leeward slope between the two phases takes two included angles β 1 ,β 2 If the distance of movement of the barchan dune between the two phases is negative, the azimuth of the movement of the foot line of the leeward slope between the two phases is the angle between the two included angles β 1 ,β 2 The larger value of ;

[0026] Calculate the two angles γ between the connecting line Y1B1 and the north-south direction 1,γ 2 : If the distance of the movement of the barchan dune between the two periods is positive, then the azimuth of the movement of the barchan dune between the two periods takes two included angles γ 1 ,γ 2 If the distance of movement of the barchan dune between the two periods is negative, the azimuth of the movement of the barchan dune between the two periods takes two included angles γ 1 ,γ 2 The larger value in .

[0027] A device for estimating motion parameters of a crescent-shaped sand dune based on remote sensing images, comprising:

[0028] The data acquisition module is used to: obtain any two periods of optical remote sensing images covering a single crescent-shaped dune to be studied;

[0029] The feature line and auxiliary line production module is used to extract the following feature lines of the crescent-shaped sand dunes from each optical remote sensing image: the foot line of the windward slope, the foot line of the leeward slope, and the sand ridge line, connect the two wing corner points of the crescent-shaped sand dunes and use the connection line as the auxiliary line;

[0030] A feature point extraction module is used to: for each feature line, select the pixel point farthest from the auxiliary line as the feature point of the feature line;

[0031] The moving distance and speed calculation module is used to: for each characteristic line extracted from the two periods, based on the distance from the characteristic point of the characteristic line in each period to the characteristic line in another period, calculate the moving distance based on the characteristic line between the two periods; and combine the moving distances of the three characteristic lines to obtain the moving distance and moving speed of the crescent-shaped sand dune between the two periods;

[0032] The moving direction determination module is used to: determine the corresponding moving direction of the windward slope foot line and the leeward slope foot line extracted at the same time based on the connection line between their feature points and the feature points of the sand ridge line; and determine the current moving direction of the crescent-shaped sand dune based on the connection line between the feature points of the windward slope foot line and the feature points of the leeward slope foot line.

[0033] Furthermore, for each characteristic line extracted from the two periods, based on the distance from the characteristic point of the characteristic line in each period to the characteristic line in another period, calculating the moving distance between the two periods based on the characteristic line specifically includes:

[0034] Suppose the characteristic lines extracted in the previous and next two phases are L1 and L2, and the corresponding characteristic points are A1 and A2 respectively;

[0035] Place feature lines L1 and L2 in the same layer based on their physical coordinate positions; then in this layer: find a point B2 on feature line L2, and the line B2A1 connecting point B2 and feature point A1 is the perpendicular line of feature line L2 at point B2, then the distance between feature point A1 and point B2 is the distance d from feature point A1 to feature line L2 1 ; Use the same method to obtain the distance d from the feature point A2 to the feature line L1 2 ;

[0036] Take the distance d 1 With distance d 2 The average value of is taken as the amplitude of the moving distance of the current calculation characteristic line between the previous and next periods;

[0037] Determine whether the vector angle between the direction from feature point A1 to feature point A2 and the southeast direction is less than 90 degrees: if the vector angle is less than 90 degrees, the moving distance between the previous and next periods of the currently calculated feature line is taken as a positive value; if the vector angle is greater than 90 degrees, the moving distance between the previous and next periods of the currently calculated feature line is taken as a negative value.

[0038] Furthermore, the average of the moving distances of the three characteristic lines, namely the sand ridge line, the foot line of the leeward slope, and the foot line of the windward slope, between the two periods is taken as the moving distance of the crescent dune between the two periods; and the moving speed of the crescent dune between the two periods is calculated according to the time interval T between the two periods, which is expressed as:

[0039]

[0040] In the formula, d and v are the moving distance and moving speed of the crescent dune between the two phases, respectively. s , d b , d y They respectively represent the movement distances of the three characteristic lines, namely the sand ridge line, the leeward slope foot line, and the windward slope foot line, between the two periods.

[0041] Furthermore, the specific method for determining the moving direction is:

[0042] Step 5.1, connecting the feature points of each feature line extracted from the previous optical remote sensing image in pairs;

[0043] Step 5.2, record the characteristic points of the windward slope foot line, leeward slope foot line and sand ridge line as Y1, B1, S1 respectively, and obtain the interconnecting lines Y1B1, B1S1, Y1S1, then:

[0044] Calculate the two angles α between the connecting line Y1S1 and the north-south direction 1 , α 2: If the distance of movement of the crescent dune between the two phases is positive, then the azimuth of the windward slope foot line moving between the two phases takes two included angles α 1 , α 2 If the distance of movement of the barchan dune between the two phases is negative, the azimuth of the windward slope foot line moving between the two phases is the angle between the two included angles α 1 , α 2 The larger value of ;

[0045] Calculate the two angles β between the connecting line B1S1 and the north-south direction 1 , β 2 :If the distance of movement of the crescent dune between the two phases is positive, then the azimuth of the movement of the foot line of the leeward slope between the two phases takes two included angles β 1 , β 2 If the distance of movement of the barchan dune between the two phases is negative, the azimuth of the movement of the foot line of the leeward slope between the two phases is the angle between the two included angles β 1 , β 2 The larger value of ;

[0046] Calculate the two angles γ between the connecting line Y1B1 and the north-south direction 1 , γ 2 : If the distance of the movement of the barchan dune between the two periods is positive, then the azimuth of the movement of the barchan dune between the two periods takes two included angles γ 1 , γ 2 If the distance of movement of the barchan dune between the two periods is negative, the azimuth of the movement of the barchan dune between the two periods takes two included angles γ 1 , γ 2 The larger value in .

[0047] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements any of the above-mentioned methods for estimating motion parameters of crescent-shaped sand dunes based on remote sensing images.

[0048] The beneficial effects of the present invention include:

[0049] (1) Accurately determine the locations of characteristic points of various characteristic lines of dunes, and ensure the accurate locations of characteristic points of dunes at different times by constructing crescent-shaped dune auxiliary lines;

[0050] (2) By calculating the distances of all pixels on each dune feature line from the auxiliary line and determining the pixel with the farthest distance as the feature point, the accuracy of determining dune feature points at different times is improved;

[0051] (3) The present invention can improve the accuracy of single dune motion parameter estimation. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 is a flow chart of the method described in the embodiment of the present application;

[0053] Figure 2 is a schematic diagram of determining feature points using the method described in an embodiment of the present application;

[0054] Figure 3 is a schematic diagram of calculating the moving distance between characteristic lines by the method described in the embodiment of the present application;

[0055] Figure 4 It is a point-line diagram of the moving distance of three characteristic lines of the crescent-shaped sand dune in the method described in the embodiment of the present application, all of which are based on the first optical image, (a) is the sand ridge line, (b) is the foot line of the leeward slope, and (c) is the foot line of the windward slope;

[0056] Figure 5 Schematic diagram of the movement direction of sand dunes estimated by the method of the embodiment of the present application, (a) is the foot line of the windward slope, (b) is the foot line of the leeward slope, and (c) is the overall movement direction of the sand dunes;

[0057] Figure 6 A wind rose diagram is made based on the wind condition data corresponding to the optical image time in the study area of ​​the embodiment of the present application, wherein the optical image times corresponding to sub-images (a)(b)(c)(d)(e)(f) are 2021.3-2021.5, 2021.6-2021.8, 2021.9-2021.11, 2020.12, 2021.1-2021.2, and 2021.12, respectively. DETAILED DESCRIPTION

[0058] The following is a detailed description of an embodiment of the present invention. This embodiment is based on the technical solution of the present invention, and provides a detailed implementation method and a specific operation process to further explain the technical solution of the present invention.

[0059] Example 1

[0060] This embodiment provides a method for estimating motion parameters of crescent-shaped sand dunes based on remote sensing images. Figure 1 As shown, the specific implementation steps are as follows:

[0061] Step 1: Obtain any two optical remote sensing images covering a single crescent-shaped dune to be studied.

[0062] This embodiment uses Sentinel-2 satellite optical images to download a total of 18 image data in 2021, with an interval of about 20 days between each image. The test area is located in the northwest of the Maowusu Desert in Inner Mongolia. The image uses RGB true color band with a resolution of 10m, which can clearly see the real ground conditions. The images are downloaded and processed, and image data with cloud cover less than 5% are screened. The images have been pre-processed by cropping and registration.

[0063] Step 2: extract the following characteristic lines of the crescent dune from each optical remote sensing image: the foot line of the windward slope, the foot line of the leeward slope, and the sand ridge line, connect the two wing corner points of the crescent dune and use the connection line as an auxiliary line.

[0064] A typical crescent-shaped sand dune was selected in the study area. The foot line of the windward slope, the foot line of the leeward slope and the sand ridge line of the dune were manually traced based on high-resolution remote sensing images, and these three characteristic lines were smoothed with a smoothing tolerance of 30m. Using the feature conversion function, all pixel points on each characteristic line can be presented and then exported.

[0065] Connect the corner points of the two wings of the crescent-shaped sand dune as an auxiliary line. Since the main wind direction in the area is not much different from the vertical direction of the dune ridge, the sand dune moves perpendicular to the direction of the dune ridge. Therefore, the auxiliary line is roughly parallel to the tangent line of the highest point of the sand ridge. Therefore, it can be considered that the straight line between the two wings of the sand dune is perpendicular to the wind direction, and it is also the representative line for measuring the width between the two wings.

[0066] Step 3: For each feature line, select the pixel point farthest from the auxiliary line as the feature point of the feature line.

[0067] For each feature line, draw a perpendicular line through each pixel point to the auxiliary line to obtain the foot point of the perpendicular. Let the coordinates of any n-th pixel point on the feature line be (x n1 ,y n1 ), the corresponding foot point coordinates are (x n2 ,y n2 ), then the distance d from the nth pixel to the auxiliary line n for:

[0068]

[0069] Select the maximum value from the distances from all pixels to the auxiliary line, and the corresponding pixel is the feature point of the feature line. Figure 2 shown.

[0070] Step 4, for each characteristic line extracted from the two periods, based on the distance from the characteristic point of the characteristic line in each period to the characteristic line of the other period, calculate the moving distance based on the characteristic line between the two periods; combining the moving distances of the three characteristic lines, obtain the moving distance and moving speed of the crescent-shaped sand dune between the two periods.

[0071] For crescent-shaped dunes under the influence of multiple wind directions, the position of the characteristic points on each characteristic line is different at different times. Therefore, the following process is used to determine the various movement distances and speeds:

[0072] Step 4.1, calculate the moving distance between two periods based on the characteristic line, specifically including:

[0073] Suppose the characteristic lines extracted in the previous and next two phases are L1 and L2, and the corresponding characteristic points are A1 and A2 respectively;

[0074] Place feature lines L1 and L2 in the same layer based on their physical coordinate positions; then in this layer: find a point B2 on feature line L2, and the line B2A1 connecting point B2 and feature point A1 is the perpendicular line of feature line L2 at point B2, then the distance between feature point A1 and point B2 is the distance d from feature point A1 to feature line L2 1 ; Use the same method to obtain the distance d from the feature point A2 to the feature line L1 2 ;

[0075] Take the distance d 1 With distance d 2 The average value of is taken as the amplitude of the moving distance of the current calculation characteristic line between the previous and next periods;

[0076] Determine whether the vector angle between the direction from feature point A1 to feature point A2 and the southeast direction is less than 90 degrees: if the vector angle is less than 90 degrees, the moving distance between the previous and next periods of the currently calculated feature line is taken as a positive value; if the vector angle is greater than 90 degrees, the moving distance between the previous and next periods of the currently calculated feature line is taken as a negative value.

[0077] Step 4.2, calculate the moving distance and moving speed of the crescent-shaped sand dune between the two periods.

[0078] The average of the moving distances of the three characteristic lines, namely the sand ridge line, the foot line of the leeward slope, and the foot line of the windward slope, between the two periods is taken as the moving distance of the crescent dune between the two periods; and the moving speed of the crescent dune between the two periods is calculated according to the time interval T between the two periods. It can be expressed as:

[0079]

[0080] In the formula, d and v are the moving distance and moving speed of the crescent dune between the two phases, respectively. s , d b , d y They respectively represent the movement distances of the three characteristic lines, namely the sand ridge line, the leeward slope foot line, and the windward slope foot line, between the two periods.

[0081] Step 5, determine the movement direction of the windward slope footline, leeward slope footline and crescent sand dune between the two periods based on the interconnected lines of the characteristic points of the windward slope footline, leeward slope footline and sand ridge line in the previous optical remote sensing image, as well as the positive and negative values ​​of the movement distance of the crescent sand dune between the two periods.

[0082] First, the feature points of each feature line extracted from the previous optical remote sensing image are connected to each other;

[0083] Then, the characteristic points of the windward slope foot line, leeward slope foot line and sand ridge line are recorded as Y1, B1, S1 respectively, and the interconnecting lines Y1B1, B1S1, Y1S1 are obtained, then:

[0084] Calculate the two angles α between the connecting line Y1S1 and the north-south direction 1 , α 2 : If the distance of movement of the crescent dune between the two phases is positive, then the azimuth of the windward slope foot line moving between the two phases takes two included angles α 1 , α 2 If the distance of movement of the barchan dune between the two phases is negative, the azimuth of the windward slope foot line moving between the two phases is the angle between the two included angles α 1 , α 2 The larger value of ;

[0085] Calculate the two angles β between the connecting line B1S1 and the north-south direction 1 , β 2 :If the distance of movement of the crescent dune between the two phases is positive, then the azimuth of the movement of the foot line of the leeward slope between the two phases takes two included angles β 1 , β 2 If the distance of movement of the barchan dune between the two phases is negative, the azimuth of the movement of the foot line of the leeward slope between the two phases is the angle between the two included angles β 1 , β 2 The larger value of ;

[0086] Calculate the two angles Y between the connecting line Y1B1 and the north-south direction 1 , Y 2 : If the distance of the movement of the barchan dune between the two periods is positive, then the azimuth of the movement of the barchan dune between the two periods takes two included angles γ 1 , γ 2 If the distance of movement of the barchan dune between the two periods is negative, the azimuth of the movement of the barchan dune between the two periods takes two included angles γ 1 , γ 2 The larger value in .

[0087] Step 6, obtaining the wind condition data for the corresponding period, and using the wind condition data to verify the direction of sand dune movement.

[0088] Obtain wind condition data corresponding to the optical image time in the study area from December 2020 to December 2021, including wind direction, wind speed, number of observations, etc., extract data with wind speed ≥ 6 m / s, draw wind rose diagrams for the four seasons, and verify the wind condition data with the sand dune movement information.

[0089] In order to verify the accuracy of the method, the motion parameters of the crescent dunes estimated by the present invention were compared with the wind conditions data in the corresponding time. The results are shown in the attached Figure 4 , 5 6: The movement direction of the sand dunes is northwest-southeast, mainly between 121°-130°, the movement direction of the foot line of the windward slope is between 107°-124°, the movement direction of the foot line of the leeward slope is between 130°-178°, and there are three periods of sand dunes with the foot line of the leeward slope moving between 326°-342°; in spring and winter, northwest winds prevail in the study area, and the characteristic parts of the crescent-shaped sand dunes move to the southeast, and in summer, southeast winds prevail, and the characteristic parts of the crescent-shaped sand dunes move to the northwest. It can be proved that the present invention is accurate in monitoring the movement of a single crescent-shaped sand dune, and can accurately estimate the dune migration process, providing a reliable basis for desertification control.

[0090] The above embodiments are preferred embodiments of the present application. Ordinary technicians in this field can also make various changes or improvements on this basis. Without departing from the overall concept of the present application, these changes or improvements should fall within the scope of protection required by the present application.

Claims

1. A method for estimating motion parameters of crescent dunes based on remote sensing images, characterized in that: include: Step 1, obtain any two periods of optical remote sensing images covering a single crescent-shaped dune to be studied; Step 2, extract the following characteristic lines of the crescent-shaped sand dune from each optical remote sensing image: the foot line of the windward slope, the foot line of the leeward slope, and the sand ridge line, connect the two wing corner points of the crescent-shaped sand dune and use the connection line as an auxiliary line; Step 3: For each feature line, select the pixel point farthest from the auxiliary line as the feature point of the feature line; Step 4, for each characteristic line extracted from the two periods, based on the distance from the characteristic point of the characteristic line in each period to the characteristic line in another period, calculate the moving distance of the characteristic line between the two periods; and combine the moving distances of the three characteristic lines to obtain the moving distance and moving speed of the crescent dune between the two periods; Step 5, determine the movement direction of the windward slope footline, leeward slope footline and crescent sand dune between the two periods based on the interconnected lines of the characteristic points of the windward slope footline, leeward slope footline and sand ridge line in the previous optical remote sensing image, as well as the positive and negative values ​​of the movement distance of the crescent sand dune between the two periods.

2. The method for estimating motion parameters of crescent dunes based on remote sensing images according to claim 1, characterized in that: The optical remote sensing image is an optical satellite image with a resolution exceeding 10 meters.

3. The method for estimating motion parameters of crescent dunes based on remote sensing images according to claim 1, characterized in that: The step of calculating the moving distance of each characteristic line extracted from the two periods between the previous and the next periods based on the distance from the characteristic point of the characteristic line in each period to the characteristic line in another period specifically includes: Suppose the characteristic lines extracted in the previous and next two phases are L1 and L2, and the corresponding characteristic points are A1 and A2 respectively; Place the feature lines L1 and L2 in the same layer based on their physical coordinate positions; then in the layer: find a point B2 on the feature line L2, and the line B2A1 connecting the point B2 and the feature point A1 is the perpendicular line of the feature line L2 at the point B2, then the distance between the feature point A1 and the point B2 is the distance d1 from the feature point A1 to the feature line L2; the distance d2 from the feature point A2 to the feature line L1 is obtained by the same method; The average value of distance d1 and distance d2 is taken as the amplitude of the moving distance of the current calculated characteristic line between the previous and next periods; Determine whether the vector angle between the direction from feature point A1 to feature point A2 and the southeast direction is less than 90 degrees: if the vector angle is less than 90 degrees, the moving distance between the previous and next periods of the currently calculated feature line is taken as a positive value; if the vector angle is greater than 90 degrees, the moving distance between the previous and next periods of the currently calculated feature line is taken as a negative value.

4. The method for estimating motion parameters of crescent dunes based on remote sensing images according to claim 1, characterized in that: The average moving distances of the three characteristic lines, namely the sand ridge line, the foot line of the leeward slope and the foot line of the windward slope, between the two periods are taken as the moving distance of the crescent dune between the two periods; and the moving speed of the crescent dune between the two periods is calculated according to the time interval T between the two periods; it is expressed as: In the formula, d and v are the moving distance and moving speed of the crescent dune between the two phases, respectively. s ,d b ,d y They respectively represent the moving distances of the three characteristic lines, namely the sand ridge line, the leeward slope foot line and the windward slope foot line, between the two periods.

5. The method for estimating motion parameters of crescent dunes based on remote sensing images according to claim 1, characterized in that: Step 5 determines the moving direction and specifically includes: Step 5.1, connecting the feature points of each feature line extracted from the previous optical remote sensing image in pairs; Step 5.2, record the characteristic points of the windward slope foot line, leeward slope foot line and sand ridge line as Y1, B1, S1 respectively, and obtain the interconnecting lines Y1B1, B1S1, Y1S1, then: Calculate the two angles α1 and α2 between the connecting line Y1S1 and the north-south direction: if the distance moved by the crescent-shaped sand dune between the two periods is a positive value, then the azimuth of the windward slope foot line moving between the two periods takes the smaller value of the two angles α1 and α2; if the distance moved by the crescent-shaped sand dune between the two periods is a negative value, then the azimuth of the windward slope foot line moving between the two periods takes the larger value of the two angles α1 and α2; Calculate the two angles β1 and β2 between the connecting line B1S1 and the north-south direction: if the distance moved by the barchan dune between the two phases is positive, the azimuth of the foot line of the leeward slope between the two phases is the smaller of the two angles β1 and β2; if the distance moved by the barchan dune between the two phases is negative, the azimuth of the foot line of the leeward slope between the two phases is the larger of the two angles β1 and β2; Calculate the two angles γ1 and γ2 between the connecting line Y1B1 and the north-south direction: if the moving distance of the crescent dune between the two periods is a positive value, then the azimuth of the movement of the crescent dune between the two periods takes the smaller value of the two angles γ1 and γ2; if the moving distance of the crescent dune between the two periods is a negative value, then the azimuth of the movement of the crescent dune between the two periods takes the larger value of the two angles γ1 and γ2.

6. A device for estimating motion parameters of crescent-shaped sand dunes based on remote sensing images, characterized in that: include: The data acquisition module is used to: obtain any two periods of optical remote sensing images covering a single crescent-shaped dune to be studied; The feature line and auxiliary line production module is used to extract the following feature lines of the crescent-shaped sand dunes from each optical remote sensing image: the foot line of the windward slope, the foot line of the leeward slope, and the sand ridge line, connect the two wing corner points of the crescent-shaped sand dunes and use the connection line as the auxiliary line; A feature point extraction module is used to: for each feature line, select the pixel point farthest from the auxiliary line as the feature point of the feature line; The moving distance and speed calculation module is used to: for each characteristic line extracted from the two periods, based on the distance from the characteristic point of the characteristic line in each period to the characteristic line in another period, calculate the moving distance based on the characteristic line between the two periods; and combine the moving distances of the three characteristic lines to obtain the moving distance and moving speed of the crescent-shaped sand dune between the two periods; The moving direction determination module is used to: determine the corresponding moving direction of the windward slope foot line and the leeward slope foot line extracted at the same time based on the connection line between their feature points and the feature points of the sand ridge line; and determine the current moving direction of the crescent-shaped sand dune based on the connection line between the feature points of the windward slope foot line and the feature points of the leeward slope foot line.

7. The device for estimating motion parameters of crescent dunes based on remote sensing images according to claim 6, characterized in that: The step of calculating the moving distance between the two periods based on the characteristic line for each characteristic line extracted from the two periods based on the distance from the characteristic point of the characteristic line in each period to the characteristic line in another period specifically includes: Suppose the characteristic lines extracted in the previous and next two phases are L1 and L2, and the corresponding characteristic points are A1 and A2 respectively; Place the feature lines L1 and L2 in the same layer based on their physical coordinate positions; then in the layer: find a point B2 on the feature line L2, and the line B2A1 connecting the point B2 and the feature point A1 is the perpendicular line of the feature line L2 at the point B2, then the distance between the feature point A1 and the point B2 is the distance d1 from the feature point A1 to the feature line L2; the distance d2 from the feature point A2 to the feature line L1 is obtained by the same method; The average value of distance d1 and distance d2 is taken as the amplitude of the moving distance of the current calculated characteristic line between the previous and next periods; Determine whether the vector angle between the direction from feature point A1 to feature point A2 and the southeast direction is less than 90 degrees: if the vector angle is less than 90 degrees, the moving distance between the previous and next periods of the currently calculated feature line is taken as a positive value; if the vector angle is greater than 90 degrees, the moving distance between the previous and next periods of the currently calculated feature line is taken as a negative value.

8. The device for estimating motion parameters of crescent dunes based on remote sensing images according to claim 6, characterized in that: The average moving distances of the three characteristic lines, namely the sand ridge line, the foot line of the leeward slope, and the foot line of the windward slope, between the two periods are taken as the moving distance of the crescent dune between the two periods; and the moving speed of the crescent dune between the two periods is calculated according to the time interval T between the two periods, which is expressed as: In the formula, d and v are the moving distance and moving speed of the crescent dune between the two phases, respectively. s ,d b ,d y They respectively represent the movement distances of the three characteristic lines, namely the sand ridge line, the leeward slope foot line, and the windward slope foot line, between the two periods.

9. The device for estimating motion parameters of crescent dunes based on remote sensing images according to claim 6, characterized in that: Specific method for determining the moving direction: Step 5.1, connecting the feature points of each feature line extracted from the previous optical remote sensing image in pairs; Step 5.2, record the characteristic points of the windward slope foot line, leeward slope foot line and sand ridge line as Y1, B1, S1 respectively, and obtain the interconnecting lines Y1B1, B1S1, Y1S1, then: Calculate the two angles α1 and α2 between the connecting line Y1S1 and the north-south direction: if the distance moved by the crescent-shaped sand dune between the two periods is a positive value, then the azimuth of the windward slope foot line moving between the two periods takes the smaller value of the two angles α1 and α2; if the distance moved by the crescent-shaped sand dune between the two periods is a negative value, then the azimuth of the windward slope foot line moving between the two periods takes the larger value of the two angles α1 and α2; Calculate the two angles β1 and β2 between the connecting line B1S1 and the north-south direction: if the distance moved by the barchan dune between the two phases is positive, the azimuth of the foot line of the leeward slope between the two phases is the smaller of the two angles β1 and β2; if the distance moved by the barchan dune between the two phases is negative, the azimuth of the foot line of the leeward slope between the two phases is the larger of the two angles β1 and β2; Calculate the two angles γ1 and γ2 between the connecting line Y1B1 and the north-south direction: if the moving distance of the crescent dune between the two periods is a positive value, then the azimuth of the movement of the crescent dune between the two periods takes the smaller value of the two angles γ1 and γ2; if the moving distance of the crescent dune between the two periods is a negative value, then the azimuth of the movement of the crescent dune between the two periods takes the larger value of the two angles γ1 and γ2.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method according to any one of claims 1 to 5 is implemented.

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